Our invention relates to lasers in general and, in particular, to a metal ion laser utilizing negative glow discharges in an atmosphere of an inert gas such as helium (He) for the vaporization of a metal such as cadmium (Cd) being heated. Still more particularly, our invention concerns an electric control system for such a laser designed for the production of a beam of stable intensity throughout the period of operation.
Metal ion lasers are capable of emitting multicolor beams by virtue of the intense excitations offered thereby. He-Cd ion lasers, for example, have so far been confirmed to emit as many as 12 different color beams including those of the primary colors. The metal ion lasers are definitely superior in this respect to liquid or solid lasers. There has, however, been a problem left unsolved with this type of laser. In a metal ion laser employing a hollow cathode, the required excitation for laser action is obtained by vaporizing cadmium or like metal and mixing the metal vapor with helium or like gas in the interior (cathode bore) of the hollow cathode. The production of an unfluctuating intensity beam by this type of laser depends in large measure in the constant metal vapor pressure in the cathode bore. As far as we are aware, there has heretofore been suggested no commercially acceptable laser equipped to automatically maintain the metal vapor pressure at a constant level.